Add validated function to DatasetProxy

The only thing it does right now is make sure that periods referred to
in related period fields (narrower, broader, derivedFrom) actually exist
in the dataset

modules/periodo-app/src/backends/dataset_proxy/index.js

@@ -5,13 +5,56 @@ const { getSort } = require('./sort')
     , PromiseWorker = require('promise-worker')
     , indexItems = require('./index_items')
 
+function copy(obj) {
+  return JSON.parse(JSON.stringify(obj))
+}
+
+const SINGLE_VALUED_RELATED_PERIOD_FIELDS = [ 'derivedFrom' ]
+    , MULTI_VALUED_RELATED_PERIOD_FIELDS = [ 'narrower', 'broader' ]
+
+
 module.exports = class DatasetProxy {
   constructor(raw) {
     this.raw = raw
     Object.assign(this, indexItems(raw))
     this.sorts = {}
   }
 
+  get validated() {
+    const validated = {
+      type: 'rdf:Bag',
+      authorities: copy(this.authoritiesByID),
+    }
+
+    const { periods, periodsByID } = indexItems(validated)
+        , periodInDataset = periodID => periodID in periodsByID
+
+    // Filter out related periods that won't exist in the target dataset. This
+    // will be the case if someone adds local period A, which references local
+    // period B, but does not add local period B.
+    for (const period of periods) {
+      for (const attr of MULTI_VALUED_RELATED_PERIOD_FIELDS) {
+        const value = period[attr]
+
+        if (!value) continue
+
+        period[attr] = period[attr].filter(periodInDataset)
+      }
+
+      for (const attr of SINGLE_VALUED_RELATED_PERIOD_FIELDS) {
+        const value = period[attr]
+
+        if (!value) continue
+
+        if (!periodInDataset(value)) {
+          delete period[attr]
+        }
+      }
+    }
+
+    return validated
+  }
+
   getWorker() {
     if (this._worker) {
       return this._worker

modules/periodo-app/src/backends/dataset_proxy/index_items.js

@@ -46,6 +46,10 @@ module.exports = function indexItems(rawDataset) {
       ;[].concat(period[relation] || []).forEach(relatedPeriodID => {
         const relatedPeriod = periodsByID[relatedPeriodID]
 
+        // It's possible that this related period might not exist, if this is
+        // a strangely formed dataset.
+        if (!relatedPeriod) return
+
         period[$$RelatedPeriods][relation][relatedPeriodID] = relatedPeriod
 
         if (inverseRelation) {

modules/periodo-app/src/backends/test/proxy.js

@@ -0,0 +1,53 @@
+"use strict"
+
+const test = require('blue-tape')
+    , DatasetProxy = require('../dataset_proxy')
+
+const danglingRelatedPeriodsDataset = {
+  authorities: {
+    p0123: {
+      id: 'p0123',
+      periods: {
+        p0123a: {
+          id: 'p0123a',
+          derivedFrom: 'p0123d',
+          broader: [
+            'p0123b',
+            'p0123c',
+          ],
+        },
+        p0123b: {
+          id: 'p0123b',
+          derivedFrom: 'p0123a',
+        },
+      },
+    },
+  },
+}
+
+test('Dataset proxy validation', async t => {
+  const dataset = new DatasetProxy(danglingRelatedPeriodsDataset)
+
+  t.deepEqual(
+    dataset.validated,
+    {
+      type: 'rdf:Bag',
+      authorities: {
+        p0123: {
+          id: 'p0123',
+          periods: {
+            p0123a: {
+              id: 'p0123a',
+              broader: [
+                'p0123b',
+              ],
+            },
+            p0123b: {
+              id: 'p0123b',
+              derivedFrom: 'p0123a',
+            },
+          },
+        },
+      },
+    }, 'should filter out related periods that do not exist')
+})